Over time, Cyber Monday has become a self-fulfilling prophesy. Consumers are conditioned to expect a rash of cyber sales when they get back to work on Monday and companies are happy to oblige.

"People love sales and can’t get enough of them," said Sucharita Mulpuru, a senior retail analyst with Forrester Research. "Very few people are tired of sales."

Companies like Amazon, Walmart, Best Buy, Macy's, Nordstrom and Target are happy to oblige.

The first Cyber Monday was in 2005. That's when Ellen Davis of the National Retail Federation came up with the term. Other suggestions were Blue Monday (after the color of web links) or Green Monday (for the money being made) — but she liked the clarity of Cyber Monday.

The idea was to leverage something that was already happening. At the time, online sales were still new. In 2004 just 10% of Americans did any holiday shopping online at all, though by 2005 it was up to around 30%, according to ComScore Networks.

A speed gauge at a San Francisco building.

People were used to going out to stores the Friday after Thanksgiving for the shopping madness that had come to be known as Black Friday — as they still do. But to shop online, they waited until they got back to work.

In part that was because most people still only had a slow dialup connection at home.

"They would begin their web shopping on the Monday they got back to work, because that's where they had access to a high speed Internet connection," said Gene Alvarez, a retail analyst at Gartner.

Within a year, Cyber Monday had embedded in our psyches, even though the reason it originally existed had faded. Today, 73% of U.S. households have broadband and 75% of Americans have smartphones, according to the Pew Research Center.

Most big box stores are advertising online deals, starting Thursday or even earlier. But there's still a reason to wait. Cyber Monday is now all about deals — and expectations.

Hitting the buy button

Adobe’s Tamara Gaffney thinks people have actually been shopping online all weekend. But they don’t hit the “buy” button until they’re convinced they've gotten the absolute best price available.

“If you look at the hourly peak times for [Cyber Monday] shopping, they come between 8:00 and 11:00 pm in each time zone,” said Gaffney, strategic insights engagement group director for Adobe.

“They know that by Monday night it’s not going any lower and if they wait until Tuesday the deals will be gone. So that’s when they hit the ‘buy’ button,” she said.

Of course there are other reasons Cyber Monday is a good shopping day, said Hunter Williams, a partner in the retail and consumer practice at the management consultant firm Oliver Wyman.

“It also means the in-laws have left, the Christmas lights have been put up and you have time to breathe and go online again, in ways you might not have been able to on Thanksgiving weekend,” he said.

Adobe predicts that U.S. online holiday sales will reach $107.4 billion this year, an increase of 13.8%, with Cyber Monday leading the way.

Holiday sales overall are predicted to be as high as $682 billion, according to the National Retail Federation, up 4% from last year.

Some 7% of people plan to do the majority of their holiday shopping on Cyber Monday, compared with 10% of Black Friday and 40% after Cyber Monday, according to TrendSource data. The rest are year-round shoppers who are done before most people have even started.

Eventually the specificity will fade, says Yory Wurmser, a senior analyst with market research firm eMarketer.